Apparatus methods of forming ditch liners are known. See, e.g., U.S. Pat. Nos. 4,872,784, 4,955,759, 4,955,760, 5,049,006, 5,062,740 and 5,145,282. These patents broadly describe a process comprising dispensing a solidifiable liquid mixture onto a continuously moving porous blanket, applying pressure against the mixture and coated blanket to form a continuous matrix within the blanket, laying the resulting coated blanket into a ditch before the liquid mixture has fully cured, conforming the coated blanket to the shape of the ditch, and allowing the mixture to fully cure.
The above noted patents give almost no guidelines as to solidifiable compositions which should be used. For example, the '784 patent (at column 5, lines 55-60), the '759 patent (at column 5, lines 58-63), the '760 patent (at column 4, lines 55-60)and the '740 patent (at column 4, lines 56-61) broadly suggest the use of a foamed polyurethane resin without describing any specific formulations. The '006 patent (at column 4, lines 26-32) and the '282 patent (at column 5, line 64--column 6, line 2) broadly suggest the use of a thermosetting resin forming mixture such as a polyester or a polyurethane forming mixture, without describing any specific formulations.
In actual practice, the solidifiable liquid mixture to be used in the process must be curable over a wide range of temperatures. Thus, for example, the composition must be curable at temperatures as low as 15.degree. F. and as high as 120.degree. F. depending upon the climate of the region where the ditch is being lined. Furthermore, the mixture must generally be curable within a reasonable amount of time (typically from 5 to 30 minutes) without any application of externally applied heat. The object of the present invention was the development of a composition which would meet these conditions of curing times and temperatures.